To get used to it, as a skinned eel, i.e. as an eel is used to being skinned. It may be unpleasant at first, but habit will get the better of such annoyance.

It aint always pleasant to turn out for morning chapel, is it, Gig-lamps? But its just like the eels with their skinning: it goes against the grain at first, but you soon get used to it.Cuthbert Bede [Bradley]: Verdant Green, chap. vii.